Performance improvements in computing and storage, along with a drive to exploit these improvements in highly challenging applications, have increased the demand for extremely fast data links, for example in areas of high-speed and data-intensive networking. One example of a highly challenging application is data replication in information storage and retrieval. For systems that are expected to operate continuously, a duplicate and fully operational backup capability is implemented in the event a primary system fails.
Data replication, which may also be called mirroring, is a process that generates a mirrored copy of information on two or more storage devices, a primary volume and one or more secondary volumes. The goal is availability of important information on duplicate storage devices at all times. The duplicates may reside on the same or different devices or systems. Similarly, the duplicates may reside on local or remote devices or systems. The obvious advantage of remote replication is avoidance of destruction of both the primary and secondary copies in the event of a disaster occurring in one location.
Corporations, institutions, and agencies sharing common databases and storage systems often include enterprise units that are widely dispersed geographically and therefore may use data replication over very large distances. Distance between storage sites increases communication latency, and reduces speed and reliability, although the demand for fast communication remains.
In response to the demand for fast data links, various network interconnect standards have been developed to enable faster communication between computers and input/output devices. One example of an interconnect standard is a Fibre Channel (FC) standard and associated variants, which are defined in an effort to facilitate data communication, including network and channel communication, between and among multiple processors and peripheral devices. The Fibre Channel standard enables transfers of large information amounts at very high rates of two or more gigabits (Gb) per second.
Remote replication links in storage systems tend to be exclusively standard links with a specified standard throughput, for example 1-2 Gb for the Fibre Channel standard. Replication links may be implemented on other standards, such as Enterprise Systems Connection (ESCON), Small Computer Systems Interface (SCSI), and others.